In the electronic equipment industry, it is common to provide leads for connection substrates, such as printed circuit boards, chip carriers, and the like, by soldering the leads to conductive pads on the substrate. See, for example, U.S. Pat. No. 4,728,305 issued Mar. 1, 1988 and U.S. Pat. No. 5,030,144 issued Jul. 9, 1991. Such substrates commonly have a row of conductive pads or contact areas along one or more edges, for connection to an array of generally parallel leads spaced correspondingly to the pad spacing. The leads are commonly connected at one end to a longitudinally extending carrier strip, so that a section of the carrier strip having a ganged array of leads extending from it, may be applied to the row of pads along one edge of the substitute for simultaneously soldering the ganged array of leads to the row of pads.
The trend in this industry has been towards greater and greater miniaturization. As a result, the spacing between conductive pads of a substrate has been progressively reduced. While a pitch of 0.100 inch (that is, 10 pads to the inch) has been common, the industry is moving more and more toward smaller pitches, such as 0.075 or 0.050 inch or even less. This requires a corresponding reduction of spacing and size of leads which are to be connected to such conductive pads.
In satisfying such needs for reduced spacing between leads, sufficient spacing must be nevertheless provided between the leads to prevent inadvertent contact or arcing between adjacent leads. This must be done without sacrificing accuracy in manufacture or impeding rapid assembly of multiple leads. A particular problem arises where the leads are solder-bearing, since in some instances the arrangement for holding the solder to the lead may encroach into the space between leads, thereby limiting how closely the leads may be spaced. See for example said U.S. Pat. No. 4,728,305.
Accordingly, a need exists for solder-bearing leads of reduced size and spacing which are effectively applicable to accommodate reduced size and spacing of substrate conductive pads, but sufficiently spaced to prevent arcing, and to provide methods of manufacturing such leads without sacrificing accuracy.